1. Field of the Invention
The present invention relates to a hydraulic circuit device which supplies hydraulic pressure to a plurality of frictional engagement elements, in an automatic transmission which, being mounted on a vehicle, can change a speed by switching a combination of an engagement and disengagement of the plurality of frictional engagement elements.
2. Description of the Related Art
Heretofore, as this kind of hydraulic circuit device, one which forms a specific speed when an electrical failure occurs, and all solenoids are deenergized, has been proposed (for example, refer to JP-A-2005-265101). This device, being provided with normally closed type solenoid valves SL1, SL2, and SL4, includes a sequence valve which, when a shift lever is in a drive (D) range, at a normal time, connects the solenoid valve SL1 to a C1 clutch, connects the solenoid valve SL2 to a C2 clutch, and connects the solenoid valve SL4 to a B2 brake, and which, at a failure time when all the solenoid valves are deenergized, connects a D range oil passage of a manual valve, which outputs a line pressure in the D range, to servos of either the C1 or C2 clutch and the B2 brake, whereby it is possible to form either a third speed gear or a fifth speed gear even at the failure time, allowing travel to continue.